Continuous method of extracting animal glue in concentrated aqueous solutions



1N V EN TOR.'

May 22, 1956 A. LOLLI CONTINUOUS METHOD OF EXTRACTING ANIMAL GLUE IN CONCENTRATED AQUEOUS SOLUTIONS Filed April 27, 1953 NNI ATTORNEY.

United CONTINUOUS METHOD OF EXTRACTING AN GLUE IN CNCENTRATED AQUEOUS SOLUTEUNS August L. Lolli, Chicago, ill., assigner to Armour and Company, Chicago, Ill., a corporation of illinois Application April 27, 1953, Serial No. 351,410

6 Claims. (Cl. 260-118) This invention relates to a continuous method of extracting animal glue in concentrated aqueous solutions.

In my co-pending application, United States Serial No. 351,409, filed April 27, 1953, for Process for Extracting Animal Glue in Concentrated Aqueous Solutions, there is described a method of extracting animal glue characterized by the step of cooking out a concentrated aqueous solution of glue by contacting conditioned, water-impregnated animal glue stock solids with an essentially water-immiscible heat transfer medium in liquid form maintained at a glue-liberating temperature. This process has the important advantage of directly producing glue extracts which are sufficiently concentrated to permit them to be gelled without subjecting the glue to an evaporating step to remove the water and thereby concentrate the glue. Furthermore, as described in my cited co-pending application, the glue can be extracted by this process in a much shorter time than heretofore and with the production of as high or higher quality glue than can now be obtained in conventional water bath extractions.

It is the general object of this invention to provide a method for carrying out an extraction process of the type described in my co-pending application, which method is adapted for continuous or semi-continuous operation. In other words, it is the principal object of this invention to provide a continuous method of extracting animal glue in concentrated aqueous solutions. Further objects and advantages will appear as the specification proceeds.

. The method of this invention is shown in an illustrative embodiment in the accompanying drawing.

In one of its aspects this invention is concerned with a method of extracting animal glue in concentrated aqueous solutions characterized by the steps of agitating conditioned, water-impregnated glue stock solids in contact with an essentially water-immiscible heat transfer medium in liquid form at a glue-liberating temperature to extract a concentrated aqueous solution of glue, withdrawing a three-phase mixture comprising the aqueous glue solution, the water-immiscible heat transfer medium, and the residual glue stocks solids, and separating the aqueous glue solution from the other phases in the mixture. More particularly, it is preferred to continue the agitation of the glue stock solids until they are reduced in particle size and the bulk of the glue extracted therefrom, withdrawing the three-phase mixture described,

2,746,950 Patented May 22, 1956 2 permit them to pass through the drum perforations to a point outside the drum.

A wide variety of water-immiscible heat transfer mediums can be employed, as described in my co-pending application cited above. For example, the heat transfer medium can be a water-immiscible organic fat solvent, which can be either of greater or lesser specific gravity than water. Excellent results are obtained with chlorinated hydrocarbons of less than three carbon atoms such as ethylene dichloride, carbontetrachloride, chloroform, etc., as well as with petroleum solvents like kerosene. The process can also be carried out with a fatty acid triglyceride as the heat transfer medium, such as animal fat of the same type as in the glue stock.

Any conditioned animal glue stock impregnated with water can be used, although in the production of highgrade glues it is preferred to employ water-swollen hide glue stock. The presence of fat in the glue stock is not objectionable, and, in fact, the process can be used for the simultaneous extraction of glue and fat. Further, the particular conditioning process employed, whether conventional lime conditioning, microorganism conditioning, acid conditioning, etc., is not of great importance, except that it is desirable to have the glue stock contain as much absorbed water as possible. For further details as to the desired nature of the glue stock and of the heat transfer medium reference is made to my copending application cited above.

Examples ditioned acid-plumped hide glue stock, is fed into thev mouth of rotating drum 11 of rotary glue extractor 12. Drum 11 is mounted to rotate in an inclined position as illustrated with its forward portion running partly submerged in a body of liquid 13, and the forward end portion of the drum is provided with a plurality of perforations 14 through which liquid and small particles can move between the interior and exterior of the drum. The forward end portion of rotary extractor 12 is provided with a steam heating jacket 15 for heating the body of liquid 13, the heat in turn being transferred from the liquid 13 to the glue stock solids within drum 11. The body of liquid 13 is preferably maintained at a temperature of from 55 to 65 C. during the glue extraction. The rotation of drum 11 continuously tumbles the glue stock solids within the drum which has a disintegrating effect on the solids and eventually reduces their size so that they will pass through perforations 14 to the exterior of the drum within the body of liquid 13. The extracted concentrated aqueous solution of glue also passes out through perforations 14 and into the body of liquid 13. The other major component of liquid body 13 is the water-immiscible heat transfer medium, such as ethylene dichloride. Within the body of liquid 13 the disintegrated glue stock solids form one phase, the concentrated aqueous solution of glue forms the second phase, and the water-immiscible heat transfer medium forms a third phase. In the operation of the method as illustrated, a portion of the liquid body 13 continuously is withdrawn from a point exterior to drum 11 through outlet 16 and passed to a three-phase centrifugal separator 17. Within separator 17 the liquid body is separated into its three phases, the disintegrated spent solids being intermittently discharged at 18, the concentrated extracted glue being discharged at 19, and the Waterl immiscible organic solvent being discharged at 20, passed to a temporary storage tank at 2l. The water-immiscible organic solvent, together with added solvent if desired, is recirculated through the rotary glue extractor through an overhead inlet 22 from which it flows downwardly over and through drum 11 and the glue stock solids therein. If desired, a solvent heater 23 can be provided in the return line -to bring the recirculated solvent up to the desired temperature within the glue extractor.

In the example given, a valve controlled overflow outlet 24 is provided for the removal of excess solvent in case it builds up within the glue extractor. The organic solvent or heat transfer medium can be removed through outlet 24 substantially free of the disintegrated particles of the glue stock and of the extracted glue. When the glue stock solids contain considerable quantities of fat, this will tend to be dissolved in the Water-immiseible organic fat solvent, but the organic solvent can be recirculated until it is substantially saturated with fat. Then, fresh solvent can be supplied to the circuit and the fatsaturated solvent subjected to distillation to recover the fat and to free the solvent of fat so that it can be reused. This procedure can be rendered unnecessary by employing as the heat transfer medium animal fat of the same kind as that in the glue stock solids. In this case, as the amount of fat builds up in the circuit due to the extraction of the fat, the excess fat can either be removed from vessel 21 or through overflow outlet 24.

While in the foregoing specification this invention has been described in considerable detail and in relation to particular embodiments thereof it will be apparent to those skilled in the art that the invention is susceptible to other embodiments and that many of the details set forth can be varied widely without departing from the spirit of the invention.

I claim:

1. ln a method of extracting animal glue, wherein animal glue stock solids are conditioned and wherein the conditioned glue stock solids are soaked in an aqueous solution to obtain water-impregnated glue stock solids, the steps of agitating said water-impregnated glue stock solids in contact with an essentially water-immiscible organic fat solvent in the absence of water other than that impregnated in said glue stock solids, said organic fat solvent being maintained at a glue liberating temperature to cook out a concentrated aqueous solution of glue, withdrawing a three-phase mixture comprising said concentrated aqueous solution of glue, the waterimmiscible organic fat solvent, and the residual glue stock solids, and separating said concentrated aqueous solution of glue from the other phases in said mixture.

2. The method of claim l in which said animal glue stock solids contain both collagen and fat and in which said organic fat solvent concomitautly dissolves said fat, displaces said collagen from the glue stock solids, and converts said collagen to glue.

3. In a method of extracting animal glue, wherein hide glue stock is conditioned and wherein the conditioned hide glue stock is soaked in water to obtain a glue stock swollen at least 100%, the steps of agitating the waterswollen glue stock in contact with an essentially waterimmiscible organic fat solvent in the absence of water other than that impregnated in said glue stock, said organic fat solvent being maintained at a glue-liberating temperature to cook out a concentrated aqueous solution of glue, continuing the agitation until said glue stock is reduced in particle size and the bulk of the glue extracted in a concentrated aqueous solution, withdrawing a three-phase mixture comprising said concentrated aqueous solution of glue, the water-immiscible fat solvent and residual glue stock, and separating each of the three phases from said mixture.

4. In a method of extracting animal glue, wherein animal glue stock solids are conditioned and wherein the couditioncd glue stock solids are soaked in an aqueous acidic solution to obtain acid-swollen glue stock solids, the

steps of tumbling said acid-swollen glue stock solids inside a perforated drum at least partially submerged in a bath of an essentially water-immiscible organic fat solvent in the absence of water other than that impregnated in said glue stock solids, said organic fat solvent being maintained at a glue-liberating temperature to cook out a concentrated aqueous solution of glue, said glue stock solids being on the average of a larger particle size than the drum perforations, continuing the tumbling action until said glue stock solids are disintegrated and passed outside of said drum through the perforations therein together with the concentrated aqueous solution of glue, withdrawing a three-phase mixture from outside of said drum comprising said concentrated aqueous solution of glue, the water-immiscible organic fat solvent, and the disintegrated glue stock solids, and separating said concentrated aqueous solution of glue from the other phases of said mixture.

5. 1n a method of extracting animal glue, wherein animal glue stock solids are conditioned and wherein the conditioned glue stock solids are soaked in an aqueous acidic solution to obtain acid-swollen glue stock solids, the steps of feeding said acid-swollen glue stock solids into a perforated drum, said glue stock solids when introduced into said drum having a larger diameter on the average than the perforations in said drum, rotating said drum in an extraction zone in contact with a waterimmiscible organic fat solvent in the absence of water other than that impregnated in said glue stock solids, said organic fat solvent being maintained at a glueliberating temperature to cook out a concentrated aqueous solution of glue, continuing the rotation of said drum until said glue stock solids are substantially disintegrated and pass outwardly through the perforations of said drum together with the concentrated aqueous solution of glue, withdrawing from the outside of said drum a three-phase mixture comprising the concentrated aqueous solution of glue, the water-.immiscible organic fat solvent and the disintegrated glue stock solids, separating the withdrawn mixture into each of its three phases, and returning at least a portion of the separated organic fat solvent to said extraction zone.

6. In a method of extracting animal glue, wherein hide glue stock solids are 'conditioned and wherein the conditioned glue stock solids are soaked in an aqueous solution to obtain water-impregnated glue stock solids, the steps of feeding said water-impregnated glue stock solids into a perforated drum, said glue stock solids containing both fat and collagen and when introduced into said drum being on the average of larger diameter than the perforations in said drum, tumbling the glue stock solids within said drum in contact with liquid animal fat of the same kind as the fat within said glue stock solids in the absence of water other than that impregnated in said glue stock solids, said liquid animal fat being maintained at a glue-liberating temperature to cook out a concentrated aqueous solution of glue together with fat from said glue stock solids, continuing the tumbling action until said glue stock solids are substantially disintegrated and passed outwardly through the perforations of said drum together with the concentrated aqueous solution of glue and the liqin'd animal fat, and recovering both the concentrated aqueous solution of glue and fat.

References Cited in the iile of this patent UNITED STATES PATENTS 89,709 Tuttle et al May 4, 1869 2,301,242 BillaudOt NOV. 10, 1942 2,562,221 Tour July 31, 1951 FOREIGN PATENTS 181,865 Great Britain June 29, 1922 

1. IN A METHOD OF EXTRACTING ANIMAL GLUE, WHEREIN ANIMAL GLUE STOCK SOLIDS ARE CONDITIONED AND WHEREIN THE CONDITIONED GLUE STOCK SOLIDS ARE SOAKED IN AN AQUEOUS SOLUTION TO OBTAIN WATER-IMPREGNATED GLUE STOCK SOLIDS, THE STEPS OF AGITATING SAID WATER-IMPREGNATED GLUE STOCK SOLIDS IN CONTACT WITH AN ESSENTIALLY WATER-IMMINSCIBLE ORGANIC FAT SOLVENT IN THE OBSENCE OF WATER OTHER THAN THAT IMPREGNATED IN SAID GLUE STOCK SOLIDS, SAID ORGANIC FAT SOLVENT BEING MAINTAINED AT A GLUE LIBERATING TEMPERATURE TO COOK OUT A CONCENTRATED AQUEOUS SOLUTION OF GLUE, WITHDRAWING A THREE-PHASE MIXTURE COMPRISING SAID CONCENTRATED AQUEOUS SOLUTION OF GLUE, THE WATERIMMISCIBLE ORGANIC FAT SOLVENT, AND THE RESIDUAL GLUE STOCK SOLIDS, AND SEPARATING SAID CONCENTRATED AQUEOUS SOLUTION OF GLUE FROM THE OTHER PHASES IN SAID MIXTURE. 